This invention relates to a wheelchair and more particularly to an attachment for a wheelchair to enable the wheelchair to traverse irregular terrain.
The conventional wheelchair is comprised of two large diameter, ground-engaging, narrow width, pneumatic rear wheels mounted on an axle positioned beneath the seat portion of the chair with smaller diameter, narrow width, pneumatic, ground-engaging wheels positioned forwardly of the rear wheels. The front wheels are pivotally mounted to vertical stanchions and generally are not able to be locked in any particular angular position. The occupant of the wheelchair is seated in a conventional fashion such that the lower portion of the occupant's legs will be generally perpendicular to the ground.
The operator of the conventional-type wheelchair, when using the wheelchair off-road, is faced with a number of problems. The conventional wheelchair also faces difficulties when traversing uneven surfaces or negotiating obstructions in the path. One difficulty is in being unable to proceed any further when a wheel becomes stuck in a depression, such that when the occupant attempts to free himself, the chair may be upset. A similar problem, with the same consequences, occurs when attempting to traverse obstructions--rocks, logs or curbs--in the pathway.
A further problem with a conventional wheelchair is that the user is unable to generate enough sustained human power to climb steep grades. Thus, the conventional wheelchair has limited capability for traversing inclines.
Applicant has attempted to solve the above-enumerated problems with previous inventions. For example, see U.S. Pat. No. 4,892,323 and my pending application, Ser. No. 439,612 filed Nov. 20, 1989 entitled "ALL-TERRAIN WHEELCHAIR." Although the all-terrain wheelchairs of the previous inventions do perform extremely well, it has been found that it may be more economical to provide an attachment for a conventional wheelchair to enhance the capabilities of the conventional wheelchair. Although the instant invention does enhance the capabilities of a conventional wheelchair, it will not have quite the stability or versatility of the previous inventions.
It is therefore a principal object of the invention to provide an all-terrain wheelchair.
A further object of the invention is to provide an attachment for a conventional wheelchair to convert the wheelchair to an all-terrain wheelchair.
A further object of the invention is to provide an attachment for a conventional wheelchair which enables the wheelchair to traverse uneven terrain.
Yet another object of the invention is to provide an attachment for a wheelchair which permits the user to generate greater driving force so that the wheelchair may traverse steep inclines.
Still another object of the invention is to provide an attachment for a wheelchair which is easily secured thereto and which is safe to use.
These and other objects of the present invention will be apparent to those skilled in the art.